Field of the Invention
The invention relates to a method and system of patterning of a film on a substrate and specifically to a method and system of enhancing the structure profile on the substrate to meet patterning objectives.
Description of Related Art
In semiconductor manufacturing, patterning of a film on a substrate can be achieved through several methods that have evolved with time to follow Moore's law. Double patterning is the technique used to create hard mask features smaller than photolithographic capabilities by using spacer deposition to define feature dimensions. Typical double patterning (DP) techniques require a sequence of deposition over a mandrel, etch to form the spacer and another etch to remove the mandrel, with both deposition and etch tools required. There are some spatial limitations inherent in the conventional DP technique due to deposition ‘thin-ness’ limitations and pitch of the features from mandrel formation limitations.
Self-aligned double and quadruple patterning and other patterning schemes require a spacer to be formed on the sidewall of a pre-patterned feature. The pre-patterned feature is then removed leaving the spacer as the mask for subsequent patterning. A lot has been done on self-aligned double patterning (SADP) and quadruple patterning (SAQP) for patterning scheme layout but not a lot has been done on focusing and tuning the spacer sidewall mask using reactive ion etch (RIE) for patterning. The spacer sidewall profile has a large impact on subsequent patterning steps in an integration scheme. There is a need for techniques using reactive ion etch to achieve a spacer sidewall mask profile that will help to achieve better profiles in subsequent patterning steps. There is also a need for fabricating a pattern that lands on silicon nitride without creating a recess on the silicon nitride, without causing an undercut in the spacer sidewall, and use current gas reactant mixtures to get high selectivity to the silicon nitride.